Downhole tool with a propellant charge

ABSTRACT

A tool for manipulating a tubular, such as casing or production tubing, in a downhole environment, this described. The tool comprises a housing defining a chamber, the chamber having at least one outlet, a propellant source located within the chamber and an ignition mechanism for igniting the propellant source. Upon ignition of the propellant source, the propellant deflagrates, creating at least one stream of combustion products, the chamber directing the stream of combustion products through the/each outlet, towards the tubular to be manipulated, the/each stream of combustion products combining with at least one modifying agent to manipulate the tubular.

FIELD

The present invention relates to a tool for manipulating a tubular, suchas casing or production tubing, in a downhole environment. Particularly,embodiments of the present invention relate to a tool for strippingcasing and cement in a well abandonment operation.

BACKGROUND

There are situations in which it is desirable to remove a portion ofcasing or tubing from an oil or gas well. A typical situation may be toremove a length of casing to allow a permanent cement plug to beinstalled, prior to well abandonment. Current Oil and Gas UK Guidelinesfor the Abandonment of Wells (July 2015, Issue 5) dictate that apermanent barrier, typically a cement plug, must be formed between thereservoir and the seabed to act as one of a number of permanent barrierswhen a well is abandoned or plugged. This measure is intended to isolatethe well and reduce the possibility of pressure migration in order toprevent hydrocarbons and other well fluids from underground reservoirsleaking past the barrier(s) and coming to surface and spilling into thesea.

In some situations, prior to installing the cement plug to abandon orplug the well, it is necessary to remove the production tubing, casingand other downhole tubulars, and the cement or other downhole fixingsthat secure the well to the bedrock.

Casing may also be removed to undertake a casing repair, or to exposethe cement behind the casing to allow cement repair. In some cases,where cemented casing is used, for example, there may be a leak path inthe cement behind the casing or between casing layers. Rectifying such abreach may also require the removal of a casing section and associatedcement before forming new cement and repairing the casing.

Conventional removal of cemented casing uses, for example, milling toolsor hydro-abrasive cutters which remove the casing and associated cementby gradually cutting or milling away small portions of metal and cement.These are slow processes and therefore make such an operation veryexpensive and time consuming.

Perforating charges have also historically been used to penetrate acasing wall, to allow fluid communication through the casing wall and toallow cementing behind. Perforations only produce small holes throughthe target, whereas large holes are often desirable.

SUMMARY

According to a first aspect of the present invention there is provided atool for manipulating a tubular in a downhole environment, the toolcomprising:

a housing defining a chamber, the chamber having at least one outlet;

a propellant source located within the chamber;

an ignition mechanism for igniting the propellant source; and

at least one modifying agent provided in or adjacent the tool orgenerated by the tool;

wherein upon ignition of the propellant source, the propellant source isadapted to deflagrate, creating at least one stream of combustionproducts, the chamber directing the stream of combustion productsthrough the/each outlet, towards the tubular to be manipulated, the/eachstream of combustion products combining with at least one modifyingagent to manipulate the tubular.

In at least one embodiment of the invention a tool is provided whichuses a stream of combustion products created by combustion of apropellant source to manipulate a tubular by, for example, ablation,cutting, displacement, removal, heating, abrasion, or erosion. Thismethod is much faster than conventional processes leading to time andresource savings, and associated reduced costs.

A propellant is an explosive material which has a low rate of combustionand once ignited burns or otherwise decomposes to produce propellantgas. This gas is highly pressurised, the pressure driving the gas andother combustion products away from the propellant, forming a stream ofcombustion products. A propellant can burn smoothly and at a uniformrate after ignition without depending on interaction with theatmosphere, and produces propellant gas and/or heat on combustion andmay also produce additional combustion products.

In use, the/each stream of combustion products and/or the modifyingagent may erode, ablate, abrade or remove at least a portion of thetubular to be manipulated.

In use, the/each stream of combustion products may heat the tubular tobe manipulated and the modifying agent may impinge at least a portion ofthe tubular to be manipulated, transferring energy to the tubular to bemanipulated.

At least a portion of the tubular to be manipulated may be forciblydisplaced or moved by the/each stream of combustion products and/or themodifying agent which impinge the tubular.

At least a portion of the tubular to be manipulated may be fractured,fragmented or cracked by the/each stream of combustion products and/orthe modifying agent which impinge the tubular.

The tool may be anchored relative to the tubular to be manipulated.The/each stream of combustion products leads to a thrust effect whichseeks to drive the tool in the opposite direction to the flow ofthe/each stream. In at least one embodiment, anchoring the tool relativeto the tubular to be manipulated, creates a powerful stream ofcombustion products which can be used with the modifying agent, tomanipulate a tubular.

The tool may be anchored to the tubular.

The propellant source may be anchored relative to the tubular to bemanipulated.

The propellant source may comprise a plurality of propellants.

Where there is a plurality of propellants, each propellant may combustseparately.

The propellants may be separated by a barrier.

The barrier may comprise a non-combustible layer.

The barrier may comprise a void.

The void may be defined by adjacent propellants.

Where there is a plurality of propellants, at least some of thepropellant sources may be ignited in a sequence.

Where there is a plurality of propellants, at least some of thepropellants may be ignited substantially simultaneously.

Where there is a plurality of propellants, at least some of thepropellants may be equidistant from an outlet.

Alternatively, at least some of the propellants may be arranged atvarying distances from an outlet.

Where there is a plurality of propellants, at least some of thepropellants may be associated with one outlet.

In alternative embodiments, where there is a plurality of propellants,at least one propellant may share an outlet with at least one otherpropellant.

The direction of the stream of combustion products may be, at any time,altered within the housing or external to the housing by biasing atleast a portion of the combustion products to a different direction.

A change in direction of the stream of combustion products may beachieved or partially achieved by a surface or surfaces protruding intothe combustion products flow path.

A change in direction of the stream of combustion products may beachieved or partially achieved by a differential pressure ordifferential pressures acting on the combustion products flow path.

A change in direction of the stream of combustion products may beachieved or partially achieved by the introduction of additional fluid,gas or solid media or a plurality of media to the combustion productsflow path.

A change in direction of the stream of combustion products may beachieved or partially achieved by a centrifugal or other accelerationforce which acts on a combustion product or combustion products.

The direction of the stream of combustion products may change withrespect to time during the tool operation.

The stream of combustion products may be singular. There may be multiplestreams of combustion products. The stream(s) of combustion products maydivide or recombine inside and/or outside of the housing. The pluralityof combustion product streams may change with respect to time during thetool operation.

The propellant source may be positioned such that the/each stream ofcombustion products flows, initially, in a direction perpendicular tothe/each stream of combustion products when the combustion products arein the tool.

Where the propellant source comprises a plurality of propellants, thepropellants may be arranged to generate streams of combustion productswhich flow in different directions and/or flow at different times.

Where the propellant source comprises a plurality of propellants, atleast one propellant may have a different function to at least one ofthe other propellants. For example, one propellant may heat the tubularto be manipulated and another propellant may erode, ablate, abrade orremove the tubular to be manipulated.

In at least one embodiment of the tool the/each stream of combustionproducts may be generated without generating heat or with minimal heatgeneration. Certain types of propellant can combust without generatingheat and the risk of igniting flammable materials that may be in closeproximity to the/each stream of combustion products is reduced oreliminated. Additionally, mineral heat generation reduces damage to thetool.

The propellant source may comprise a solid propellant.

Alternatively or additionally, the propellant source may comprise aliquid, paste, foam or gel propellant.

The propellant source may be wholly contained within the housing.

In alternative embodiments, the propellant source may be fed into thehousing. Feeding the tool with propellant allows the tool to be usedcontinuously. The propellant source may be fed into the housing in theform of pellets.

The propellant source may be fed into the housing either continuously orintermittently.

The propellant source may be formed by combining two or more materialswithin the tool.

The propellant source may be arranged to create an intermittent streamof combustion products.

The propellant source may be a single state, a solid, liquid or gas ormay be in two or more states.

Alternatively the propellant source may comprise propellants in separatestates, which are combined at or prior to combustion initiation.

Alternatively or additionally the propellant sources may change stateprior to ignition.

The propellant source may comprise a covering.

The covering may cover a section of the surface of the propellantsource, the covering defining an aperture, the aperture exposing thesurface portion of the propellant, the exposed surface portion being theportion of the surface which deflagrates. The covering prevents oxygenreaching the propellant surface allowing the area of the propellantsurface which burns and the rate of propellant burn to be controlled.

The covering may control the direction of flow of the/each stream ofcombustion products.

Once ignited, the propellant source may define a combustion zone.

As the propellant source deflagrates, the combustion zone may moverelative to the tubular to be manipulated.

The tool may further comprise at least one deflector for deflectingthe/each stream of combustion products. The/each stream of combustionproducts may be deflected multiple times before reaching a target.

The/each deflector may define a deflection surface.

The/each deflector may be movable.

The/each deflector may be positioned in the path of the/each stream ofcombustion products.

The/each deflector may move into the path of the/each stream ofcombustion products.

The/each deflector may move out of the path of the/each stream ofcombustion products.

The/each deflector position may be controlled by a motor and/oractuator.

The/each deflector may be arranged to deflect the/each stream ofcombustion products towards an outlet.

The/each deflector may be arranged to split the/each stream ofcombustion products.

The/each deflector may be arranged to change the direction of the/eachstream of combustion products.

The/each deflector may maintain a substantially constant distance fromthe combustion zone.

The/each deflector position may be controlled by reacting with the/eachstream of combustion products.

The/each deflector position may be controlled by the combustion process.

The/each deflector may alter in response to the/each stream ofcombustion products.

The/each deflector profile may change in response to thermal and/orpressure input from the/each stream of combustion products and/orsurroundings.

The/each deflector profile may change due to erosion from the/eachstream of combustion products.

In at least one embodiment the/each deflector comprises a sacrificialsurface.

In at least one embodiment of the present invention the/each deflectorhas a coating which is gradually eroded, ablated, abraded or removed bythe/each stream of combustion products. As the deflector is altered itchanges the profile of the deflector, which in turn changes thegeometric vector and/or position of the/each stream of combustionproducts.

In at least one embodiment of the present invention the/each deflectoris bimetallic with multiple layers of metal with different thermalexpansion ratios. In response to thermal input the deflector shape isaltered.

A stream of combustion products may be deflected or moved by anotherstream of combustion products interaction. In at least one embodiment ofthe present invention the/each stream of combustion products impingeswith the/each opposing stream of combustion products, which deflectsthe/each stream of combustion products from its original geometricvector.

The deflector(s) may bifurcate the/each stream of combustion productsinto two or more stream of combustion products.

The deflector(s) may divide the/each stream of combustion products intotwo or more constituent parts.

The deflector(s) may manipulate the/each stream of combustion productsinto a desired shape.

The deflector(s) may impart rotation to the/each stream of combustionproducts.

The/each stream of combustion products may be parallel to the housingand deflected outwardly by a deflector.

There may be a plurality of outlets.

The outlet(s) may extend circumferentially around the housing.

The outlet(s) may extend axially along the housing.

The outlet(s) may define a circular cross-section. A circular outletwill facilitate the generation of a stream of combustion products.Similarly, a stream of combustion products could be generated by anoutlet of square cross-section or any outlet which has a cross-sectionof similar breadth and width. Outlets such as these could punch holes into the tubular to be manipulated.

Alternatively or additionally, the outlet(s) may be elongate. Anelongate outlet will facilitate the generation of a plane of combustionproducts.

Where the outlet(s) is elongate, the outlet(s) may also be convoluted.

Where there are a plurality of outlets, there may be a combination ofelongate and non-elongate outlets.

Where the outlet(s) extend axially along the housing the outlet(s) mayopen over a period of time.

In this embodiment, each outlet or sections of an outlet may opensequentially along the length of the tool.

The outlet(s) may be sealed.

In at least one embodiment, the outlet(s) may be sealed by an openingmechanism.

The opening mechanism may be adapted to open the outlet(s) in responseto an environmental condition being reached. For example, the openingmechanism may be adapted to open the outlet(s) when pressure inside thetool housing reaches a certain level. This may be useful where, forexample, the environmental pressure outside the tool housing is higherthan the pressure within the tool housing prior to ignition of thepropellant source. Providing a sealed outlet prevents fluid in theenvironment surrounding the tool from entering tool through the outlet.Upon ignition of the propellant source, the pressure inside the housingrises and at a threshold pressure, higher than the environmentalpressure, the outlet(s) can open allowing the/each stream of combustionproducts to exit the outlet(s).

The opening mechanism may comprise a frangible portion. The frangibleportion may be adapted to break or shear at a threshold pressure.

In alternative embodiments, the opening mechanism may be adapted to openin response to a signal, for example from surface.

The/each stream of combustion products may be intermittent through theoutlets.

At least one outlet may eject a stream of combustion products withdifferent properties than other outlets. In at least one embodiment ofthe present invention a stream of combustion products with differentproperties than another stream of combustion products may be used toproduce a different effect. For example, when removing casing and cementin a well abandonment operation, one stream of combustion products couldcut the metallic casing and the other stream of combustion productscould shatter and/or remove the cement behind the casing.

At least a portion of at least one outlet may point obliquely outwardsfrom the tool housing.

At least a portion of at least one outlet may point perpendicularlyoutwards from the tool housing.

At least a portion of each of a plurality of outlets may point inconvergent directions.

In at least one embodiment of the present invention convergent outletscreate a stream of combustion products that has greater penetration intothe target material than the/each stream of combustion products createdby a single outlet.

At least some of the/each outlet may point in convergent directions andtheir respective stream of combustion products converge at or beyond thetarget surface.

At least some of the/each adjacent outlet may point in convergentdirections and their respective stream of combustion products convergebefore reaching the target surface.

In at least one embodiment of the present invention the/each outlet maybe a nozzle having a nozzle inlet and a nozzle outlet, the nozzle beingin fluid communication with chamber.

In at least one embodiment of the present invention the/each nozzledirects or biases the/each stream of combustion products in a particulardirection. The/each nozzle can include a venturi or de laval or similargeometry to expand and/or accelerate the/each stream of combustionproducts, which imparts greater speed and/or kinetic energy to the/eachstream of combustion products from the tool.

Additionally the/each nozzle imparts a desired shape to the/each streamof combustion products which is ejected from the tool.

At least one of the/each nozzle may be moveable with respect to the toolhousing. In at least one embodiment of the present invention moveablenozzles are used to penetrate the target forming closed shapes that aresubsequently removed with ease. With moveable nozzles, the shapes can becreated without moving the entire tool.

In at least one embodiment of the present invention nozzles arepositioned on movable arms, allowing the tool to pass through narrowrestrictions and expand to bring the arms closer to the target whenthrough the restriction.

At least one of the/each moveable nozzle may move defining a pattern onthe tubular to be manipulated.

Where the at least one outlet comprises a plurality of outlets, at leastone outlet may face in an opposite direction to at least one otheroutlet. Such an arrangement, in some embodiments, will serve to balancethe tool, as the thrust generated by the/each stream of combustionproducts through opposite facing outlets will balance.

The thrust force from an outlet may be used to move the tool in a well.

The thrust force from an outlet may be used to bring the tool intocloser proximity to the target.

The thrust force from an outlet may be used to move components withinthe tool.

In at least one embodiment of the present invention the thrust from thetool moves the outlet in a circular path to cut circular sections fromthe target.

The pressure generated by the combustion process may be used to move thetool.

The pressure generated by the combustion process may be used to bringthe tool into closer proximity to the target.

The pressure generated by the combustion process may be used to movecomponents within the tool.

The chamber within the tool may maintain a constant volume.

In at least one embodiment of the present invention the pressuregenerated by the combustion process moves the propellant within the toolto maintain a constant volume chamber.

At least one of the/each stream of combustion products may be linear.

At least one of the/each stream of combustion products may becircumferential.

At least one of the/each stream of combustion products may impart arotation to the/each stream of combustion products.

At least one modifying agent may be formed by the combustion of thepropellant source.

Alternatively or additionally, at least one modifying agent may beformed separately from the combustion of the propellant source.

Alternatively or additionally, at least one modifying agent may bepresent prior to ignition of the propellant source.

The/each modifying agent may be solid, liquid and/or gas or anycombination thereof.

At least one modifying agent may be contained within the propellantsource. For example the at least one modifying agent may be exposed asthe propellant source combusts.

In at least one embodiment at least one modifying agent introduces newchemicals to the combustion process.

In at least one embodiment at least one modifying agent reacts with thepropellant constituent(s).

In at least one embodiment at least one modifying agent may react as aresult of the combustion temperature.

In at least one embodiment at least one modifying agent may react withthe combustion products and/or the/each stream of combustion products.

In at least one embodiment at least two modifying agents may react witheach other.

In at least one embodiment at least one modifying agent may react withthe environment and/or the target material(s).

In at least one embodiment at least one modifying agent may influencethe combustion process.

In at least one embodiment at least one modifying agent may change stateduring and/or after the combustion process.

In at least one embodiment at least one modifying agent may beintroduced into the propellant gas and/or combustion products.

In at least one embodiment at least one modifying agent may be drawninto the propellant gas and/or stream of combustion products by aventuri or similar geometric profile.

In at least one embodiment at least one modifying agent may bemechanically or forcibly introduced into the propellant gas and/orstream of combustion products.

In at least one embodiment at least one modifying agent may already bepresent in the tubular to be manipulated.

In at least one embodiment of the present invention at least onemodifying agent may include solid particles. Solid particles can causeabrasion of the material to be manipulated.

Alternatively or additionally at least one modifying agent may containliquid droplets. Liquid droplets can cause erosion of the material to bemanipulated.

The liquid droplets may be explosive and may explode on impact with thetarget. In at least one embodiment of the present invention explosiveliquid droplets increase the penetrating power of the/each stream ofcombustion products and/or additional materials.

In at least one embodiment of the present invention at least onemodifying agent may include a chemical etching compound. In at least oneembodiment of the present invention a chemical etching compound maycomplement the eroding power of the/each stream of combustion productsand/or additional materials by reacting with the target material.

The modifying agent may become part of the/each stream of combustionproducts within the housing.

The modifying agent may become part of the/each stream of combustionproducts outwith the housing.

The modifying agent may be applied to the surface of the tubular to bemanipulated.

In some embodiments, the modifying agent may be a flux. The flux may beapplied to the surface of the tubular to be manipulated providing amethod of transferring heat from the/each stream of combustion productsto the tubular to be manipulated material.

The housing may include a sacrificial portion.

The housing may be pressure and/or heat containing.

In at least one embodiment, the/each stream of combustion products mayerode, ablate, abrade or remove the sacrificial housing portion, erosionof the sacrificial housing portion releasing at least one modifyingagent into the/each stream of combustion products.

The/each stream of combustion products may impart heat to the modifyingagent.

The/each stream of combustion products may impart velocity to themodifying agent.

The/each stream of combustion products may impart a chemical reaction tothe modifying agent.

The tool may further include a sealing mechanism.

The sealing mechanism may be adapted to form a seal to isolate a sectionof tubular to be manipulated. The use of two or more seals may bedesirable to isolate a section of tubular to be manipulated to, forexample, remove well fluids from the section or to reduce pressurewithin the section to maximise the manipulative effect of the tool onthe tubular to be manipulated.

In at least one embodiment of the present invention the sealingmechanism is a packer or sealing element above and/or below the housing.

The tool may comprise an enhancing mechanism for enhancing the/eachstream of combustion products.

In some embodiments the enhancing mechanism may change the flowcharacteristics of the/each stream of combustion products.

The flow characteristics which may be changed include, but are notlimited to, the thrust on the/each stream of combustion products orenergy in the/each stream of combustion products or the direction ofthe/each stream of combustion products.

In these embodiments, the enhancing mechanism may be the application ofan eddy current to the/each stream of combustion products.

The eddy current may be pulsed.

The enhancing mechanism may impart additional energy to the/each streamof combustion products or change the shape and/or direction of the/eachstream of combustion products.

In these embodiments, the additional energy or the shape and/ordirection change may be imparted to the/each stream of combustionproducts by ionisation.

The/each stream of combustion products may be at least partially ionisedby at least part of the/each stream of combustion products coming intocontact with an electrical arc.

The/each stream of combustion products may be ionised by passing throughan induction coil.

In these and alternative embodiments, the additional energy or the shapeand/or direction change may be imparted to the/each stream of combustionproducts by passing at least a portion through a magnetic field and/orelectric field, or through a source of microwave radiation.

The enhancing mechanism may be able to generate the modifying agent inthe well. For example hydrocarbons could be burned to generateparticles.

Alternatively aluminium coated with an oxidiser could be burned togenerate sapphire-like particles.

In further alternatives, a metal rod could be introduced adjacent thetubular to be manipulated, the metal rod melting into the/each stream ofcombustion products to form molten metal with which to melt the tubularto be manipulated.

The enhancing mechanism may be oxygen to enhance the burning of thepropellant or the tubular to be manipulated. In some embodiments, thetubular to be manipulated itself can become a fuel source. Where thetubular to be manipulated is iron, introduction of oxygen and heat canform iron oxides which burn.

In some embodiments, the enhancing mechanism may be a treatment tochange the physical properties of the tubular to be manipulated. Forexample the tubular to be manipulated may be cooled by the applicationof liquid nitrogen, liquid carbon dioxide or any other suitable coolingfluid, to make it shatter more easily.

The enhancing mechanism may be the introduction of an additional form ofpropellant. For example a magnesium rod could be introduced which woulddecay to form a propellant.

In further alternatives, the enhancing mechanism could be the productionof a gas, in some embodiments through propellant combustion, whichdisplaces the fluid in the vicinity of the tool. The tool then producesa stream of combustion products, which interacts with the target in agaseous environment, with increased efficiency.

The enhancing mechanism may be an acid. In at least one embodiment ofthe present invention the tool may release an acid wash to remove anycement remaining in the borehole section that is to be repaired afterthe casing has been cut and removed during a well abandonment operation.

The ignition mechanism may comprise a pyrotechnic igniter, anelectro-pyrotechnic igniter, an electrical igniter, a chemical igniter.

Where the igniter is an electrical igniter, the electrical igniter maycomprise a bridgewire.

Alternatively or additionally the electrical igniter may be adapted tocreate a spark.

According to a second aspect of the present invention there is provideda method of manipulating a tubular in a downhole environment, the methodcomprising the steps of:

positioning a tool having a housing defining a chamber, the chamberhaving at least one outlet; a propellant source located within thechamber; and an ignition mechanism for igniting the propellant sourceadjacent a tubular to be manipulated,

igniting the propellant source such that at least one stream ofcombustion products is generated, the chamber directing the/each streamof combustion products through the/each outlet, the outlet directingthe/each stream of combustion products towards the tubular to bemanipulated, the/each stream of combustion products including amodifying agent to modify the tubular to be manipulated.

The method may further comprise the step of increasing thrust ofthe/each stream of combustion products.

The method may further comprise the step of increasing the energy ofthe/each stream of combustion products.

The method may further comprise the step of changing the direction ofthe/each stream of combustion products. The thrust or energy of the/eachstream of combustion products or the direction of flow of the/eachstream of combustion products may be changed, for example, by applyingan eddy current, an electromagnetic field, microwaves or applying aninduction force to the/each stream.

The method may further comprise the step of applying a shockwave to thetubular to be manipulated.

The method may further comprise the step of changing the physicalproperties of the tubular to be manipulated.

The method may further comprise the step of cooling the tubular to bemanipulated. This may be achieved by the application of liquid nitrogen,liquid carbon dioxide or any other suitable cooling fluid.

The method may further comprise the step of applying mechanical force tothe tubular to be manipulated. The application of mechanical force,subsequent to manipulation of the tubular to be manipulated by themodifying agent, can assist in removal of the tubular to be manipulatedand associated cement, either between tubulars or between the tubularand the bedrock.

According to a third aspect of the present invention there is provided atool for manipulating material in a downhole environment, the toolcomprising:

a confined propellant source;

an ignition mechanism for igniting the propellant source;

wherein upon ignition of the propellant source, the propellantdeflagrates, creating at least one stream of combustion products, thepropellant source being confined such that the/each stream of combustionproducts are directed towards the material to be manipulated.

The tool may comprise a housing.

The propellant source may be confined in a housing.

In other embodiments the tool housing may comprise the propellantsource.

The housing may define a chamber, the chamber having at least oneoutlet.

The propellant source may be directed towards the material to bemanipulated through the chamber outlets.

The propellant source may be located within the chamber.

The tool may further comprise at least one modifying agent, themodifying agent combining with the/each stream of combustion products tomanipulate the material.

The material may be a tubular.

The/each stream of combustion products may be directed towards aninternal or external surface of the tubular.

According to a fourth aspect of the present invention there is provideda tool for manipulating a material, the tool comprising:

a body defining a chamber for housing at least one propellant source;

at least one nozzle, the/each nozzle having an inlet and an outlet, thethe/each inlet being in fluid communication with the chamber; and

at least one mechanism for igniting the/each propellant sources;

wherein, upon ignition, at least one of the propellant sources combuststo release a combustion jet which, in use, flows out of the tool throughthe/each nozzle outlet towards a material to be manipulated.

The combustion jet may be at least one stream of combustion products.

The body may be a housing.

According to a fifth aspect of the present invention there is provided amethod of penetrating a section of tubular, the method comprising:

providing a tool, the tool comprising

-   -   a body defining a chamber for housing a propellant,        -   at least one nozzle, the/each nozzle having an inlet and an            outlet, the/each inlet being in fluid communication with the            chamber and    -   at least one mechanism for igniting the propellant;        -   wherein, upon ignition, the propellant releases a gas which            flows out of the tool through the/each nozzle outlet in the            form of at least one gas jet towards, in use, a tubular            surface to be penetrated;    -   running the tool into the tubular at a desired location; and    -   penetrating the internal surface of the tubular with the/each        gas jet.

According to a sixth aspect of the invention there is provided a methodto remove a section of casing or tubing from a downhole location, themethod comprising:

providing a tool, the tool comprising

-   -   a body defining a chamber for housing a propellant,        -   at least one nozzle, the/each nozzle having an inlet and an            outlet, the/each inlet being in fluid communication with the            chamber and    -   at least one mechanism for igniting the propellant;        -   wherein, upon ignition, the propellant releases a gas which            flows out of the tool through the/each nozzle outlet in the            form of at least one gas jet towards, in use, a tubular            surface to be penetrated;

running the tool into the casing at a desired location;

-   -   penetrating the internal surface of the casing with the/each gas        jet; and    -   removing fragments of casing from their original location.

According to a seventh aspect of the invention there is provided amethod of plugging an oil or gas well to be abandoned or decommissioned,the method comprising:

providing a tool, the tool comprising

-   -   a body defining a chamber for housing a propellant,        -   at least one nozzle, the/each nozzle having an inlet and an            outlet, the/each inlet being in fluid communication with the            chamber and    -   at least one mechanism for igniting the propellant;        -   wherein, upon ignition, the propellant releases a gas which            flows out of the tool through the/each nozzle outlet in the            form of at least one gas jet towards, in use, a tubular            surface to be penetrated;        -   the body of the tool may itself be a propellant cast;            running the tool into the casing at a desired location;    -   penetrating the internal surface of the casing with the/each gas        jet;    -   removing fragments of casing and cement from their original        location; and    -   providing cement to form a plug.

It will be understood that features listed as preferable non-essentialin respect of one aspect may be equally applicable to another aspect andare not repeated for brevity.

BRIEF DESCRIPTION OF THE DRAWINGS

embodiments of the present invention will now be described withreference to the accompanying drawings in which:

FIG. 1 is a side view of a tool for manipulating casing shown positionedin a section of a well according to a first embodiment of the presentinvention;

FIG. 2 is a section of the tool FIG. 1;

FIG. 3 is a section of the tool of FIG. 1 during deflagration of thepropellant source;

FIG. 4 is a section of the tool of FIG. 1 during deflagration of thepropellant source;

FIG. 5 is a section of the tool of FIG. 1 during deflagration of thepropellant source;

FIG. 6 is a section of the well of FIG. 1 after the tool has beenremoved and a cement plug fitted;

FIG. 7 is a side view of a tool for manipulating casing shown positionedin a section of a well according to a second embodiment of the presentinvention;

FIG. 8 is a section of the tool FIG. 7;

FIG. 9 is a section of the tool of FIG. 7 during deflagration of thepropellant source;

FIG. 10 is a section of the tool of FIG. 7 during deflagration of thepropellant source;

FIG. 11 is a section of the well of FIG. 7 after the tool has beenremoved;

FIG. 12 is a section of the well of FIG. 7 following installation of acement plug; and

FIG. 13 is a section of a tool for manipulating casing shown positionedin a well during deflagration of the tool's propellant source accordingto a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Reference is first made to FIG. 1, a side view of a tool, generallyindicated by reference numeral 10, for manipulating casing 12 in a well14 according to a first embodiment of the present invention. The casing12 is shown attached to bedrock 16 by cement 18. Particularly, the tool10 is for removing a section of the casing 12 and the cement 18attaching the casing to the bedrock 16, to permit a cement plug to beinstalled in this section in advance of the well 14 being abandoned.

The tool 10 is lowered in to the well on a wireline 19 and anchored inposition by three circumferentially displaced anchors 46 (of which oneis visible on FIG. 1) to prevent axial movement of the tool 10, as willbe explained in due course.

Additionally referring to FIG. 2, a section through the tool 10 of FIG.1, it can be seen that the tool 10 comprises a housing 20 defining achamber 22, the chamber 22 having a series of outlets 24 in the form ofnozzles.

Inside the chamber 22 is a propellant source 26 containing a propellant27 and particles of a modifying agent 28, in this case aluminium oxide.The propellant source 26 has a coating 30 which defines an opening 32 atan end of the coating 30, the opening 32 exposing a section 36 of thepropellant 27 to the interior of the chamber 22. Adjacent the exposedpropellant section 36 is an ignition mechanism 38 adapted to ignite thepropellant section 36.

Directly below the propellant 27 is a deflector plate 39 defining aprofiled deflection surface 40, the deflection surface 40 being profiledto direct a flow towards the outlets 24.

Operation of the tool 10 will now be described with reference to FIGS. 3and 4, sections of the tool 10 of FIG. 1 showing the tool 10 in use.Referring firstly to FIG. 3, with the anchors (not shown in this Figure)in place, the ignition mechanism 38 has ignited the exposed propellantsection 36 creating a combustion zone 42 on the propellant source 26. Asthe propellant 27 deflagrates, a stream of highly pressurised combustionproducts 44 is released. The stream of combustion products 44 is drivendownwards away from the propellant 27 due to the pressure within thestream 44 and, in particular, generated at the combustion zone 42.Within the stream of combustion products 44 are the particles 28 ofaluminium oxide which have been released from the propellant source 26.The thrust created by the stream of combustion products 44 is preventedfrom driving the tool 10 upwards by the anchors 46, therefore the thrustdrives the stream 44 and the particles 28 towards the deflector plate39.

The stream of combustion products 44 containing the particles 28 impactson the deflector plate 39 and are deflected along the deflection surface40 towards the outlets 24. The combustion products 44 and the particles28 are funnelled through these nozzles 24 and impact on the casing 12.

The four nozzles 24 are spaced equidistant around the circumference ofthe housing 20, the nozzles 24 being arranged in opposed pairs. Thisarrangement keeps the tool 10 centralised in the well 14 as the thrustgenerated at each nozzle 24 is countered by the thrust generated by thenozzle 24 on the opposite side of the housing 20. However, the nozzles24 are angled to the radius of the tool 10 such that the thrustgenerated by the nozzles 24 cause the tool 10 to rotate, such that thestream of combustion products 44 and the associated particles 28 cut acircumferential ring through the casing 12.

The stream of combustion products 44 has burned the aluminium oxideparticles 28 such that they have sapphire-like properties. The stream ofcombustion products 44 has also accelerated the particles 28 and thiscombination of speed and heat induced change of properties results inthe particles 28 carving into the casing 12 by displacing the casingmaterial. In addition the stream of combustion products 44 heats thecasing 12, facilitating the removal of material by the particles 28.

Referring to FIG. 4, the removal of the casing 12 strips back the casing12 leaving exposed regions 60 of cement 18.

Referring to FIG. 5, as propellant source 26 deflagrates, the coating 30burns with it, exposing new propellant 27 to the combustion zone 42.With the deflagration of the propellant source 26 under control, theanchors 46 can be partially released to permit the tool 10 to riseslowly of the well 14 and create an extended section of exposed cement18.

Once the propellant source 26 is exhausted, the exposed cement 18 can beremoved. This cement 18 is weakened by the heat and the tool 10 is runin again (not shown) and the anchors 46 are applied to the weakenedcement, causing the cement 18 to crumble and fall away leaving anexposed section 62 of bedrock 16 (FIG. 6).

This exposed section 62 can then be plugged with a cement plug 64permitting the well 14 to be abandoned.

Reference is now made to FIG. 7, a tool 110 for manipulating casing 112in a well 114 according to a second embodiment present invention.

The arrangement of the tool 110 and the surrounding well 114 is similarto that of the first embodiment and similar reference numerals have beenused, incremented by 100. The tool 110 is for a similar purpose; that isto strip a section of casing 112 and associated cement 118 from bedrock116.

The tool housing 120 includes an elongate lattice outlet arrangement124. The outlet arrangement 124 extends the entire length of the housing120.

Referring to FIG. 8, a section through the tool 110 of FIG. 7, thisFigure shows the propellant source 126 as being much wider than thepropellant source 26 of the first embodiment, the propellant source 126filling the entire width of the housing 120.

Beneath the propellant source 126 is a void 154, the purpose of whichwill be discussed in due course.

As can be seen most clearly from FIGS. 7 and 8, the outlet 124 containsa frangible seal 150 which extends up the outlet 124 to above the top ofthe void 154. From the top of the seal 150 upwards, the outlet 124 issealed by the propellant source covering 130. It will be noted there isno deflector plate on this embodiment.

The tool 110 of this embodiment further includes upper and lower packerseals 156, 158 for sealing a wellbore section 160.

Operation of the tool 110 will now be discussed. The tool 110 is loweredinto position and the upper and lower packers 156, 158 are set to sealthe wellbore section 160. It is in the section 162 that the casing 112is to be manipulated.

Referring to FIG. 9, the ignition mechanism 138 (shown on FIG. 8) isactivated and this ignites the exposed propellant section 136 creating astream of combustion products 144 which fill the void 154. Pressurebuilds up inside the void 154 until a threshold pressure is reachedwhich overcomes the strength of the frangible seal 150 breaking the sealand allowing the stream of combustion products to flow through theoutlet 124.

As the outlet 124 is a slot rather than a circular nozzle, the flow ofcombustion products 144 comes out as a blade 180 rather than as a jet.

The housing 120 is made of a sacrificial material. As the flow ofcombustion products 144 passes through the outlet, the flow 144 skimsoff the housing edges 182 which define the outlets 124. A sacrificialmaterial comes off in particulate form and becomes entrained in the flow144, the particles 128 acting as the modifying agent 128 which ispropelled onto the surface of the casing 112 to strip back the casing112, leaving exposed regions of cement 160.

Referring to FIG. 10, a section view of the tool 110 of FIG. 7, as thepropellant source 126 deflagrates, the coating 130 burns with itrevealing more of the outlet 124.

Referring to FIG. 11, a section through the well 114 after the casing112 has been stripped back to the cement 118 by the tool 110 of FIG. 7,once the propellant source 126 has fully deflagrated, a latticearrangement of grooves 184 carved into the casing 112 showing theexposed cement 118.

Application of mechanical force, for example, on the well section 162will remove the remaining casing fragments 186 and the exposed cement118. Then, as per the first embodiment, a cement plug 164 can beinstalled in the well section 162, permitting the well 114 to beabandoned.

Reference is now made to FIG. 13, a tool 210 for manipulating casing 212in a well 214 according to a third embodiment present invention.

The arrangement of the tool 210 and the surrounding well 214 is similarto that of the first embodiment and similar reference numerals have beenused, incremented by 200. The tool 210 is for punching holes in asection of casing 212 and associated cement 218 through to the bedrock216.

The primary differences between the tool 210 of this embodiment and thetool 10 of the first embodiment resides in, first, the outlets of thetool 210 being in the form of nozzles 224 which extend around thecircumference of the tool 210. These nozzles 224 are directed downwardlyto maximise the effect of moving casing material by impacting the casingat an acute angle.

The second difference resides in the deflector plate 239 which is asacrificial plate from which the stream of combustion products 244scours off the modifying agent 228. The stream of combustion products244 with the entrained modifying agent 228 punch a ring of holes 290through the casing 212 and cement 218.

Various modifications may be made to the above-described embodimentswithout departing from the scope of the invention. For example thenozzles may change the characteristics of the stream of combustionproducts by, for example, being cooled or being impregnated withmaterial or being sonically resonated or by having a surface which istextured or grooved.

In other embodiments, the stream of combustion products may impartadditional energy to the tubular. This energy may be in the form ofheat. Additionally, the stream of combustion products may exert apressure on the tubular. Alternatively or additionally the combustionproducts may exert a force on the tubular. For example, particulatewithin the combustion products and carried within the stream may impactthe surface of the tubular and exert a force. This additional energy canbe used to dislodge the manipulated casing and the associated cementsecuring it to the bedrock. There may be more than one mode ofinteraction with the tubular. For example, the tubular may be heated tomelting point while at the same time subjected to pressure.

In further embodiments, the combustion products may enhance thermalconductivity by forming a flux or thermally conductive layer at thetubing or the combustion products may react at the tubular or in transitto the tubular. For example, particles may chemically react or combustat the tubing.

1. A tool for manipulating a tubular in a downhole environment, the toolcomprising: a housing defining a chamber, the chamber having at leastone outlet; a propellant source located within the chamber; an ignitionmechanism for igniting the propellant source; and at least one modifyingagent provided in or adjacent the tool or generated by the tool; whereinupon ignition of the propellant source, the propellant source is adaptedto deflagrate, creating at least one stream of combustion products, thechamber directing the stream of combustion products through the/eachoutlet, towards the tubular to be manipulated, the/each stream ofcombustion products combining with at least one modifying agent tomanipulate the tubular.
 2. The tool of claim 1, wherein in use, the atleast one modifying agent cracks, displaces, erodes, ablates, abrades orremoves at least a portion of the tubular to be manipulated. 3-4.(canceled)
 5. The tool of claim 1, wherein the propellant sourcecomprises a plurality of propellants. 6-10. (canceled)
 11. The tool ofclaim 1, wherein the propellant source is formed of the combination oftwo or more materials within the tool.
 12. The tool of claim 1, whereinthe propellant source is arranged to create an intermittent stream ofcombustion products. 13-45. (canceled)
 46. The tool of claim 1, whereinat least one of the at least one modifying agent is formed by thecombustion of the propellant source.
 47. The tool of claim 1, wherein atleast one of the at least one modifying agent is formed separately fromthe combustion of the propellant source.
 48. The tool of claim 1,wherein at least one of the at least one modifying agent is presentprior to ignition of the propellant source.
 49. The tool of claim 1,wherein at least one of the at least one modifying agent is presentwithin the propellant source.
 50. The tool of any claim 1, wherein atleast one of the at least one modifying agent is aluminum oxide.
 51. Thetool of claim 1, wherein at least one of the at least one modifyingagent reacts with the environment and/or the tubular to be modified. 52.The tool of claim 1, wherein at least one of the at least one modifyingagent is introduced into the stream of combustion products.
 53. The toolof claim 1, wherein at least one of the at least one modifying agent isdrawn into the stream of combustion products by a venturi or similargeometric profile.
 54. The tool of claim 1, wherein at least one of theat least one modifying agent is mechanically or forcibly introduced intothe propellant gas and/or stream of combustion products.
 55. The tool ofclaim 1, wherein at least one of the at least one modifying agent isapplied to the surface of the tubular to be manipulated.
 56. The tool ofclaim 1, wherein at least one of the at least one modifying agent is aflux. 57-68. (canceled)
 69. A method of manipulating a tubular in adownhole environment, the method comprising: positioning a tool having ahousing defining a chamber, the chamber having at least one outlet; apropellant source located within the chamber; and an ignition mechanismfor igniting the propellant source adjacent a tubular to be manipulated,igniting the propellant source such that at least one stream ofcombustion products is generated, the chamber directing the/each streamof combustion products through the/each outlet, the outlet directingthe/each stream of combustion products towards the tubular to bemanipulated, the/each stream of combustion products including amodifying agent to modify the tubular to be manipulated. 70-89.(canceled)